Youth use of e‐liquid flavours—a systematic review exploring patterns of use of e‐liquid flavours and associations with continued vaping, tobacco smoking uptake or cessation

BACKGROUND AND AIMS: There is concern that young people may be attracted to e‐liquid flavours, prompting long‐term vaping in naive users and potentially subsequent tobacco smoking. We aimed to review the use of e‐liquid flavours by young people and describe associations with uptake or cessation of both regular vaping and tobacco smoking, adverse effects and subjective experiences. DESIGN: Systematic review, including interventional, observational and qualitative studies reporting on the use of e‐cigarette flavours by young people (aged < 18 years). SETTING: Studies published in English language from any country or cultural setting. PARTICIPANTS: Young people and their carers (aged < 18 years). MEASUREMENTS: A meta‐analysis was not possible due to substantial heterogeneity, inconsistency in reporting of flavour categorizations and non‐interventional study designs; thus, we narratively report findings. FINDINGS: In total, 58 studies were included. The quality of the evidence was extremely low. Most (n = 39) studies were cross‐sectional survey designs. In total, 11 longitudinal cohort studies assessed trajectories; eight qualitative studies reported on user experiences. Studies reported views and experiences of a total of 512 874 young people. Both cross‐sectional and longitudinal studies suggested that flavours are important for initiation and continuation of vaping. Qualitative evidence shows interest and enjoyment in flavours. There was judged to be insufficient evidence that use of e‐liquid flavours specifically is associated with uptake of smoking. No studies found clear associations between flavours and cessation in this population. We found no included reports of adverse effects of flavours. CONCLUSIONS: Flavours may be an important motivator for e‐cigarette uptake, but the role of flavours in tobacco smoking uptake or cessation is unclear. The quality of the evidence on use of e‐cigarette flavours by young people is low overall.